Considerable progress has been made in the last several years in increasing the sugar yield of sugarcane by improving the varieties being planted, enriching the soil with fertilizers and irrigating the soil in climates which do not naturally provide sufficient moisture for optimum plant growth. More recent efforts in improving sugar production have increasingly turned toward the use of chemicals in modifying the controlling of the physiological processes of sugarcane, particularly in ripening prior to harvest. See U.S. Pat. Nos. 3,245,775; 3,291,592; 3,482,959; 3,482,961; 3,493,361; 3,505,056; 3,660,072; 3,671,219; 3,482,961; 3,870,503; 3,897,240; and 2,992,186 for example.
With some compounds previously suggested for this purpose, there has been some concern about their resistance to breakdown in the plant and their persistence in the soil when the intended use of the sugar is nutritive as opposed to industrial (e.g. in fermentation processes). Consequently, extensive efforts continue to be made in searching for effective chemical agents that can be used to modify the ripening of sugarcane so as to increase the sucrose yield therefrom.
Generally speaking, chemicals selected for evaluation have been of types which have been previously found active in work with other plants as plant hormones, herbicides or inhibitors of growth of terminal buds, or active in killing the spindle of cane upon topical micro-application, etc. However, among the compounds heretofore found to be useful for such other special purposes, surprisingly few have been found effective in controlling the ripening of sugarcane in the desirable manner. No predictable relationship has been recognized to date between (a) the chemical structure of such compounds, (b) their phytotoxic effects, or (c) their physiological effects on the morphogenetic development of the plant, and their activity in having positive effects on ripening. In other words, the effectiveness of a compound in controlling the ripening of sugarcane and thereby increasing sugar yield remains essentially unpredictable, and the search for suitable agents continues to be fundamentally empirical.
Isobutyrate salts of Group 1 of the Periodic Table and isobutyrate ethyl esters are known as sugarcane ripening agents. See. L. G. Nickell, U.S. Pat. No. 3,870,503 and application Ser. No. 671,790 referenced above. However, isobutanol, n-propanol and ethyl alcohol for this use are believed novel and unpredictable.